Sea Technology

NOV 2018

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32 ST | November 2018 helped us to conduct safe and effi- cient CTD operations at 443 casts during seven cruises, free of any of the problems typically associated with armored cables. Effects on Scientific Data Rotation and related motions of the CTD package may cause errors in the data. Consider the SBE 9plus CTD system by Sea-Bird Scientific, widely used for high-quality hydro- graphic measurements. This system measures seawater temperature and conductivity in a duct, using a pump to regulate the speed of the water and ensure that the two mea- surements are made on the same parcel of seawater. The regulated flow causes predictable viscous heating around the temperature probe, but, in our experience, mo- tions of the CTD package may cause temperature fluctuations of about 0.6 millikelvin. Because salinity is calculated from temperature, con- ductivity and pressure data, such temperature fluctuations may have an effect in the deep ocean where the signal-to-noise ratio is low. A recent innovation uses fast-re- sponse thermistors attached to the CTD package to estimate turbu- lence. Because variability in the fall rate of the CTD package influences that estimation, rotation and other motions of the CTD package should be minimized as much as possible. Together, the underwater slip ring swivel, a stabilizing fin and a traction winch that compensates for the ship's motion create a combina- tion that helps ensure high-quality CTD and related measurements in the deep ocean. Acknowledgments We thank Katsuhisa Maeno (JAMSTEC) for support in the use of the slip ring swivel and the az- imuth/inclination meter during the RV Mirai and RV Kaimei cruises. We also thank Rei Ito (Marine Works Japan Ltd.) for collecting data with the simple azimuth meter in cruise MR17-07C of RV Mirai. References For a list of references, contact Hiroshi Uchida at huchida@jams ST Dr. Hiroshi Uchida is a physical oceanographer in the Global Chemical and Physical Ocean- ography Group at the Research and Develop- ment Center for Global Change at JAMSTEC. He holds a Ph.D. from Kyushu University and joined JAMSTEC in 2001, where he is responsi- ble for high-quality CTD measurements of GO- SHIP repeat hydrography. Yosaku Maeda is an engineer in the Underwa- ter Vehicle Engineering and Operation Group at the Department of Marine Technology Devel- opment at JAMSTEC. He has been at JAMSTEC since 2008 and is responsible for the develop- ment of instruments for underwater vehicles and observation systems. Soichi Kawamata is a product manager at Hanayuu Co. Ltd. He holds a B.E. from the Department of Industrial Physics, Engineering at Chubu University. He develops control de- vices for machine tools and ROVs. He founded Hanayuu in 2014 to produce underwater slip ring swivels. & LINEAR For mor building amplifiers to drive reactive loads. 7263 Engineer Rd., San Diego, CA 92111-1493 (858) 571-1111 FAX (858) 571-0188 Copyright 2018 isit our Model S16-20 A A 20% duty 35 x 31.5 x 35.5 inches; 985 lbs.

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